Subconscious screen: detail view with post-fork entries

Track fork point in run_forked(), capture entries added during the
run. Subconscious screen shows these in a detail view (Enter to
drill in, Esc to go back) — only the subconscious agent's own
conversation, not the inherited conscious context.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/mind/mod.rs

@@ -100,6 +100,8 @@ pub struct SubconsciousSnapshot {
     pub turn: usize,
     pub walked_count: usize,
     pub last_run_secs_ago: Option<f64>,
+    /// Entries from the last forked run (after fork point).
+    pub last_run_entries: Vec<crate::agent::context::ConversationEntry>,
 }
 
 impl SubconsciousAgent {
@@ -111,6 +113,7 @@ impl SubconsciousAgent {
             turn: self.auto.turn,
             walked_count: self.auto.walked.len(),
             last_run_secs_ago: self.last_run.map(|t| t.elapsed().as_secs_f64()),
+            last_run_entries: self.auto.last_run_entries.clone(),
         }
     }
 }